As described in Patent Literature 1 or 4, in recent years, in a manufacturing site of optical display units, Roll-to-Panel (RTP) manufacturing apparatus and manufacturing method are employed.
In the RTP method, generally, an optical display device is continuously manufactured as follows. First, a web of optical film laminate is fed from a roll. The optical film laminate is configured as including a web of carrier film, an adhesive layer laminated to one of opposite surfaces of the carrier film, and a web of optical film laminated on the carrier film via the adhesive layer.
The optical film may be a single-layered or multi-layered film. On the web of optical film laminate fed from the roll, slit lines in a width-wise direction are continuously formed to thereby form a sheet of optical film including the adhesive layer, a so-called optical film sheet, between adjacent slit lines.
The optical film sheet continuously supported on the web of carrier film is peeled with the adhesive layer from the carrier film by a peeling means arranged against or near a laminating position, and sent to the laminating position. Each of the optical film sheets which has reached to the laminating position is laminated with one of opposite surfaces of a panel member separately conveyed to the laminating position by a laminating means provided at the laminating position.
In a case of a liquid crystal display, a panel member having an optical film sheet laminated on one of opposite surfaces is laminated with another optical film sheet on the other of the opposite surfaces. When performing lamination on the other of the opposite surfaces, the another optical film sheet peeled with an adhesive layer from another web of carrier film by another peeling means is sent to a laminating position same as or different from the position where the first optical film sheet and the panel member were laminated, and laminated with the other of the opposite surfaces of the panel member.
With the spread of such RTP method, regardless of increase in speed in continuous manufacturing and growth in size of the optical display unit, required in the manufacturing apparatus and manufacturing method of the optical display unit, the lamination accuracy of 1 mm or less is required in reality for that a narrow width bezel is in demand.
Essentially, in the RTP method, it is not easy to position the flexible optical film sheet including the adhesive layer to be peeled from the web of carrier film to the rectangular panel member conveyed to the laminating position, with accuracy. Nevertheless, now, solutions for three problems; increase in speed, growth in size, and high accuracy, are required in the RTP manufacturing apparatus or manufacturing method.
A specific technical problem to be solved is that, in sequentially peeling the optical film sheet continuously laminated to the web of carrier film of the web of optical film laminate, having slit lines crossing a longitudinal direction, from the carrier film, and laminating with the corresponding rectangular panel member to continuously manufacture the optical display unit, deviation in a transverse direction and/or flopping of the optical film are caused due to loosening and/or difference in tension on both sides of the optical film laminate, which occur at the time of conveying the optical film laminate. Also, another problem to be solved is that how variation in lamination accuracy of the panel member and the optical film sheet, which occurs due to the deviation in the transverse direction and/or the flopping of the optical film laminate, can be controlled. More specifically, the problem to be solved is to realize the RTP manufacturing apparatus or manufacturing method which allows for controlling such variation.
Conventionally, as described in Patent Literature 4 or 5, a posture of a panel member has been adjusted so that it is aligned with a deviated position of an optical film sheet which deviation is caused due to deviation in a transverse direction and/or flopping of an optical film laminate which occur at the time of conveying the optical film laminate. However, along with the narrow width bezels in recent years, it is becoming difficult with the above adjustment to meet the demand of laminating the optical film sheet with the panel member with high accuracy, responding to increase in speed and growth in size.
More specifically, Patent Literature 4 describes as that, as shown in FIG. 6 thereof, a center line of the sent optical film sheet is aligned to a center line of the panel member for lamination. However, the inventors considered the deviation of the optical film sheet due to deviation in the transverse direction and/or flopping caused by loosening in tension on both sides of the optical film laminate which occur at the time of conveying the optical film laminate, as a new technical problem to be solved for realizing the lamination with high accuracy responding to the increase in speed and growth in size, not considering the above as predetermined conditions, and actively challenged such problem to arrive at a solution.
For solving such problem, first, it is necessary to use a peeling means by which the optical film sheet is certainly peeled with the adhesive layer from the carrier film of the conveyed optical film laminate without causing any deviation in the transverse direction and/or flopping. The peeling means in the RTP method generally employs a structure having a wedge-shaped cross section or a knife-shaped structure shown in FIG. 10 of Patent Literature 1 or FIG. 5 of Patent Literature 4. Of course, a rotating drum having a suctioning fixing part shown by a suction drum of FIG. 8 of Patent Literature 2 and/or a laminate drum of FIG. 9 of Patent Literature 3 can be used as the peeling means in addition to the above.